An American PhD sounds tougher than here in the UK, or at the very least significantly longer. Here, you get funding for three (or sometimes four) years and I don't know of that many people who have left their programmes.
Why is there such a big difference, and is there any data about how this this reflected in later careers?
I would guess that the advice of "only do a PhD if you want to be an academic" doesn't hold as strongly over here. Does it?
(Disclaimer: I say this as someone currently debating whether or not to do a PhD, but who doesn't want to be an academic.)
The differences are more than US versus UK. It's more US versus Europe.
I spent a semester in Ph.D. school in Denmark, and I noticed what you describe: 4 years guaranteed funding with a boot at the end.
What this means is that at the end of four years, a student has to staple all the papers they wrote, back-solve for a unifying "thesis" and then defend. No matter what.
In general, this is why Europeans Ph.D.s tend to need a postdoc, whereas American Ph.D.s can (usually) transition directly to faculty jobs.
The US Ph.D. student is encouraged to hang on and continue publishing with their advisor while they're on a hot streak and for as long as the grant funding lasts.
This allows US profs to turn the last couple years of their Ph.D. students into postdocs paid at grad student wages.
I think the OPs comment was about computer science in particular, but even there things are changing somewhat. Partially it's because of the weak economy and scarcity of faculty jobs, but getting into the top-tier places almost requires a postdoc these days.
I don't know if the "boot at the end" thing is standard even in Europe. Many places simply stop giving you money and your advisor won't be able to help you as much, but you're free to hang around until you're done. My girlfriend for example recently finished her PhD (on time), and there where a couple of PhD students hanging around her department who had been there for close to a decade.
This is not true for all countries. In Sweden you get kicked out with no PhD if you haven't finished in eight years. And that is clock years. (You can get on or two extra years for childbirth and military service I seem to remember)
Depending on the school grad students are not necessarily cheaper to a professor than Postdocs due to the overhead/fees paid for students versus that paid for postdocs. Also the current academic job market in the US is bad. Taking a postdoc for 1,2,3 years has been very common in Computer Science for people seeking faculty positions in the last couple of years.
I've heard that it's possible (not easy) for statistics Ph.D.s to jump directly to faculty positions, but I think this is becoming less common. I think that economics Ph.D.s also often jump directly to faculty positions.
An American PhD is mainly employed to be an assistant to their supervisor, and gets to study a bit on the side. An English PhD is mainly funded to study, and does a bit of assisting/teaching as an apprenticeship to become an academic themselves. This means that in England the candidate gets to spend more hours/week actually working on their PhD, so it takes fewer years overall.
Quite a lot of people in the UK get paid as contract researchers (Research Associates or Research Assistants) where you pretty much get a decent wage to do work that will probably count towards a PhD.
I'd say this isn't the norm. Some of my colleagues who've been funded this way only got the money since they were unable to get other scholarships at the time. So their supervisor managed to scrape enough together to 'hire' them.
This has downsides since the student is effectively an employee of the lab. I've seen examples where conflict arose between what the lab needed from it's RA and what the student needed in order to progress with research work.
Things could well have changed - my experience was in the late 80's and 90's. Of the people I knew RAs usually took a bit longer to get their PhDs than full time students - say 4 years rather than 3. However, the prof running the lab I was in was pretty good about giving RAs time to do their thesis while getting paid from a project.
Some of our collaborators are in the UK, so we discuss some of this stuff sometimes.
My understanding is that they are given 3 years for their PhD and do not necessarily take any courses. With a British BS being 3 years, their total time to PhD is 6 years, whereas (for physics) the average time in the US is 4+6=10 years. Not knowing anything else about two fresh PhD grads, I would take the one trained in the US over the one from UK.
Basically yes. But more specifically, graduate students in American universities will have had 2+ years of courses and have performed 4+ years of research. My understanding is that PhD students in the UK just finish at the end of the third year. In the US, you are basically done, when your project is completed.
You're on the right lines, but it's not time itself that's important ;)
I'm a British student taking my PhD in the US. The core difference is publication record: in the UK, publications while doing your PhD are simply nice to have. In the US, they are essential. This is one of the key time-stretchers (alongside having to take classes and being able to change your thesis at any time).
This roughly means that a PhD that has just graduated in the US is immediately hirable all over the world, whereas a European will not be able to take a job in the US until they've spent time building a publication portfolio after graduation.
People specialise earlier in the UK, so a PhD in the States requires a longer run-up to get students to the point where they have sufficient background in a particular field to do research in it.
Without being disrespectful to our American brothers I think the difference stems from the poor school system in the USA. Because of that the first few years of undergraduate are equivalent to European schools' last years (in breadth and a little harder in depth).
By the end of undergraduate they will have very much cached up (American schools may be bad, but Unis are top notch) but then in places like UK, students would have been a lot more focused. So once you move to PhD the first couple of years in the USA are more similar to what in the UK we call a master. Hence only the last few years of the PhD correspond to the 3 years of the European phd.
Overall I think the two system are equivalent in duration, it's just that in the USA they start from a lower step of the ladder.
(on top of this there may be difference in the focus: e.g. papers vs. thesis, but I am only talking about the durations.)
Why is there such a big difference, and is there any data about how this this reflected in later careers?
I would guess that the advice of "only do a PhD if you want to be an academic" doesn't hold as strongly over here. Does it?
(Disclaimer: I say this as someone currently debating whether or not to do a PhD, but who doesn't want to be an academic.)